1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method.
2. Description of the Related Art
Solid-state imaging apparatuses are required to improve S/N ratios and increase dynamic ranges. To meet such requirement, Japanese Patent Application Laid-Open No. 2002-223350 discloses a technique that takes at least two images in different exposure conditions, and synthesizes the images acquired at a long exposure time and a short exposure time to form an image with a wide dynamic range. Japanese Patent Application Laid-Open No. 2003-230158 discloses a technique of synthesizing multiple images that are generated from one imaging device and have different sensitivity characteristics to form an image with a wide dynamic range.
Unfortunately, in the method disclosed in Japanese Patent Application Laid-Open No. 2002-223350 that takes at least two images in different exposure conditions and synthesizes the images, a time difference in taking images to be synthesized occurs. Accordingly, when a still image of a moving object is taken, a malfunction, such as overlapping imaging on the moving part, occurs. There is thus a problem in that it is difficult to apply the technique disclosed in Japanese Patent Application Laid-Open No. 2002-223350 to moving images in terms of image quality.
In the method disclosed in Japanese Patent Application Laid-Open No. 2003-230158 that generates multiple images with different sensitivity characteristics from one imaging device to synthesize the images, pixels with multiple sensitivity characteristics are provided in the imaging device. There is thus a problem in that spatial interpolation for generating images with the respective sensitivity characteristics lacks image information other than information on the pixels with the corresponding sensitivity characteristics. The technique disclosed in Japanese Patent Application Laid-Open No. 2002-223350 causes a problem in that at least two images with different sensitivity characteristics are synthesized, the synthesized sensitivity characteristics form line graphs, and the gradation of the image residing over an inflection point is degraded.
The present invention intends to solve at least one of the above problems.